Speaking in a forthcoming Russian TV documentary, Mr Putin said a meeting with officials had been held on 22-23 February to plan the rescue of Ukraine's deposed president.

"I invited the leaders of our special services and the defence ministry to the Kremlin and set them the task of saving the life of the president of Ukraine, who would simply have been liquidated," he said.

"We finished about seven in the morning. When we were parting, I told all my colleagues, 'We are forced to begin the work to bring Crimea back into Russia'."

The trailer for The Path To The Motherland was broadcast on Sunday night with no release date announced.

The formal annexation of Crimea sparked unrest in eastern Ukraine on 7 April, when pro-Russian protesters occupied government buildings in Donetsk, Luhansk and Kharkiv demanding independence.

A month later, pro-Russian separatists in Donetsk and Luhansk declared independence from Ukraine after unrecognised referendums.

Ukraine responded by launching an "anti-terrorist operation" against them and the region became engulfed in a conflict which has cost at least 6,000 lives and driven more than a million people from their homes, according to the UN.

The Ukrainian government, Western leaders and Nato say there is clear evidence that Russia is helping the separatists with heavy weapons and soldiers. Independent experts echo that accusation.

Moscow denies it, insisting that any Russians serving with the rebels are "volunteers".

Full details of Mr Yanukovych's escape from Ukraine are unclear although Mr Putin spoke of preparations to evacuate him from Donetsk.

"Heavy machine guns were placed there, so as not to waste time talking," he added, with preparations made by land, sea and air.

The documentary, which Russian TV says will be broadcast soon, was made by Andrei Kondrashov, a journalist with state-run channel Rossiya-1.